Random thought on reliability.

[Eeveevolve]

I was thinking this morning. If you had an infinite stretch of track and infinite supply of diesel on board DMUs and set all the trains currently in use in the UK going at full pelt, which ones would break down first?

I was thinking that some of the older things like 142s (Shudder) would last a long time as they would want to get to the end of the track, and no stop starts would help.

Your thoughts?

 

[Yew]

Hmm. I.suppose it's new and complicated. Vs old and simple. I guess newer stuff would get further. However an older train may be easier to bodge together and get going again...

 

[talltim]

Are you working on purely time-to-breakdown or is a formula also involving distance covered also required?

 

[Eeveevolve]

Time to breakdown. It will be Pay-per-view. Gotta make the money back somehopw. ;p

 

[sprinterguy]

Surely the miles per casualty (failure) figures would answer this question thoroughly?

Using Modern Railways "Miles per Technical Incident" figures from December 2012 (Presumably the figures from December 2013 have been, or will shortly be, published, but I haven't seen them), which is a more stringent measure than a total failure, then First Great Western's class 180s are at the bottom of the pile, behind Northerns' 142s, ATWs' 158s and Chilterns' loco-hauled sets.

 

[Oswyntail]

Surely the miles per casualty (failure) figures would answer this question thoroughly?....

Do these figures include safety related failures (eg doors not working)? Would such failures be relevant to the current test?

 

[sprinterguy]

Do these figures include safety related failures (eg doors not working)? Would such failures be relevant to the current test?

As the technical incident number takes into account all incidents that cause a delay to a train of three minutes or more then, yes, these figures will include such failures admittedly.

However, surely when considering the cumulative effect of the rate of occurrence of these technical incidents it is not outlandish to assume that a high rate of occurrence suggests a higher risk of outright mechanical failure (as irrelevant technical incidents such as door failure would only ever form a proportion of the total), even if the actual values themselves are of little consequence?

 

[DownSouth]

Surely the miles per casualty (failure) figures would answer this question thoroughly?

No!

The vast majority of the workload for a DMU/DEMU is sustained in stopping and starting, which you would get only once at the very start in a non-stop "run until it fails" scenario.

Just to mix it up a little, some trains would consistently achieve shorter distances in this sort of test than their average distance between failures, due to a non-stop run with infinite fuel supply not having the facility for conducting routine servicing which occurs on a regular basis even if it doesn't break down.

 

[sprinterguy]

No!

The vast majority of the workload for a DMU/DEMU is sustained in stopping and starting, which you would get only once at the very start in a non-stop "run until it fails" scenario.

Back to the drawing board then As the stated reliability of any given train type is apparently meaningless in this hypothetical scenario, has anybody got a better idea?

Or in order to answer this little problem once and for all, will we actually have to find an infinite test track (Siemen's loop at Krefeld (EDIT: Wildenrath) might do, although would uneven tyre wear become an issue?), and carry this out for real, in a Top Gear-esque challenge? I mean, how hard can it be?

 

[DownSouth]

Back to the drawing board then As the stated reliability of any given train type is apparently meaningless in this hypothetical scenario, has anybody got a better idea?

I would guess that those with better electronic engne/traction control systems and power to spare at the rated top speed (i.e. fourth-generation multiple units from the late 1990's onwards) would do best, while third-generation multiple units (from the early 80's to mid 90's) would fail early due to their rated top speed being to closer to their actual top speed or even unattainable without a long descent.

Modern DMUs also have longer servicing intervals, the biggest change in European railway operations from the 80's to now having been the steps taken to reduced the amount of time that a rail vehicle is losing money by doing something other running services.

Based on all that, I would nominate a Class 150 or 153 as the probable loser by any measure, while the Class 185 would come out as the best of the British units but still comfortably covered by the Budd RDC-1 or RDC-2, a fair number of which are still in daily service heading on 60 years after they were built.

Or in order to answer this little problem once and for all, will we actually have to find an infinite test track (Siemen's loop at Krefeld might do, although would uneven tyre wear become an issue?), and carry this out for real, in a Top Gear-esque challenge? I mean, how hard can it be?

You would need a bigger loop than the Siemens track at Wildenrath to allow the faster units to go at top speed, and one with a figure eight layout as well. A big balloon loop (radius 5,000+ metres) at either end of a
very long straight would also do, with the turn being taken to the left at one end and the right at the other as is done on coal flows.

 

[Eeveevolve]

Funnily enough I was on a 185 stuck behind a late running 150 into leeds that got me thinking
about this.

 

[pemma]

I think it would depend whether people are loaded on the train or not. Pacers can really struggle if they are overcrowded, while Sprinters don't struggle so much.

 

[Beveridges]

142s are absolute garbage BUT they are damn reliable.


The first trains to break down would probably be class 47s.

 

[tbtc]

142s are absolute garbage BUT they are damn reliable

The good thing about a Pacer is that they are so simple that there's not a lot that can go wrong on them (compared to younger complicated stock with their on board computers) - it's a bit like saying that Fred Flintstone's car was simpler than a Formula One vehicle - simplicity isn't everything.

 

[pemma]

142s are absolute garbage BUT they are damn reliable.

According to Merseytravel the 156s are more reliable than the 142s.
--- old post above --- --- new post below ---

The good thing about a Pacer is that they are so simple that there's not a lot that can go wrong on them (compared to younger complicated stock with their on board computers) - it's a bit like saying that Fred Flintstone's car was simpler than a Formula One vehicle - simplicity isn't everything.

I'm not sure if the definition has changed but when I was at school we were told things like digital watches and calculators contain micro computers so by that definition you could claim the door controls on a Pacer is a computerised system. Although from my experience of Pacers the most likely thing to go wrong while they are in service is a set of doors not opening even after they've been released by the guard.

 

[Chrisgr31]

Southern keep telling us that their Class 171's are the most reliable modern diesel fleet, so if Southern are right they should be up the top somewhere.

 

[DownSouth]

Southern keep telling us that their Class 171's are the most reliable modern diesel fleet, so if Southern are right they should be up the top somewhere.

That may be true, but a more interesting figure to look at would be the miles per visit to the shed for maintenance - are they genuinely reliable or does a heavy maintenance schedule mask their true form?